Digital still cameras for photographing still images; camera devices, such as digital video cameras, for taking moving images; and a range of electronic devices, in which a digital camera is installed, are now in wide use. This has led to a growing risk that images taken unintentionally or by chance will include subjects protected under copyright, portrait rights, or other rights to privacy (hereinafter collectively called “protection targets”); or that taken images or their image data will spread. Moreover, a function for imaging and recording moving images for a short period is now also provided in most digital cameras and some camera phones. Furthermore, images captured by digital cameras and camera phones, including subjects that require protection, can also be distributed instantaneously worldwide via the Internet.
On the other hand, the faces of people are frequently captured by monitor cameras installed on streets and at ATM terminals, convenience stores, public facilities, companies, factories, and so on with the aim of protecting public amenities, ensuring security, and preventing crime. These pieces of image data, created based on images captured by monitor cameras, are not always handled with consideration to privacy protection. A range of protection technologies have therefore been proposed to protect the images or image data of these subjects to be protected.
One known protection technology is to obscure a subject to be protected if it is included in a camera shooting field, by masking the subject to be protected. In other words, portrait rights are protected by hiding protected subjects. Likewise, a technology for making protected subjects unidentifiable, in spite of the protected subject having been captured, is proposed in Patent Literature 1, for example.
A conventional camera has a function to obscure an image, such as by applying a computer-generated mosaic. More specifically, the conventional camera is designed to apply a mosaic to a part of the image in the image data obtained by photography, immediately after pressing a button for a mosaic mode, unless an appropriate password is input. FIGS. 10A and 10B show an example of image 201 taken using this type of conventional camera. FIG. 10A is an example of image 201 taken using a normal mode without using the mosaic mode. FIG. 10B shows an example of image 201 taken using the mosaic mode. As shown in FIG. 10B, the user can set area 203 for obscuring subject 202 to be protected, which is a part of image 201, when the mosaic mode is selected.
Another technology for protecting images of subjects and their image data is the use of a digital watermark embedded in an image so as to clearly indicate that the subject requires protection and block photography of this image. This technology is disclosed in Patent Literature 2. Still another technology for blocking the photography of a protected subject is the use of a device that transmits information on the protected subject, such as an IC tag. This technology is disclosed in Patent Literature 3.
However, the structure of the conventional camera disclosed in Patent Literature 1 requires the user to manually designate the image area of a protected subject and set an area for applying protection before starting photography. This may result in a failure to designate it appropriately during video photography. The structure of the camera disclosed in Patent Literature 2 and Patent Literature 3 enable protection of the entire shooting field. However, even if a protected subject is just a part of the shooting field, it is not possible to apply protection to the protected subject only. In addition, these conventional technologies cannot automatically detect protected subjects. Accordingly, if a protected subject moves or changes, it cannot be automatically followed.
Patent Literature 1: Japanese Patent Unexamined Publication No. 2003-87632
Patent Literature 2: Japanese Patent Unexamined Publication No. 2005-151124
Patent Literature 3: Japanese Patent Unexamined Publication No. 2005-223601